1. Field of the Invention
The present invention relates to a technique for managing a service lifetime of a member or a unit mounted in an image forming apparatus.
2. Description of the Related Art
In the related art, a configuration is known where a non-volatile memory is provided to a toner cartridge or a process cartridge as a detachable image forming unit, and service lifetime information such as guarantee information and/or operating information of the cartridge is stored in the non-volatile memory (see Japanese Laid-Open Patent Application No. 2001-22230 (Patent Document 1) and Japanese Laid-Open Patent Application No. 2006-30929 (Patent Document 2)).
According to Patent Document 1, the guarantee information of the process cartridge converted into the number of rotations of a photosensitive member, the number of times of recording operations of a transfer member or the number of pixels is stored in the non-volatile memory. Then, the guarantee information of the process cartridge is compared with the actual one of the number of rotations of the photosensitive member, the number of times of recording operations of the transfer member or the number of pixels. Then, from the comparison result, the service lifetime of the process cartridge is determined, and the user is notified to replace the process cartridge.
Further, according to Patent Document 1, for particular replaceable parts or devices (hereinafter, referred to as replacement members) included in the process cartridge, the guarantee information of each replacement member prescribed as the number of times of replacement of the photosensitive member (information of the maximum number of times of recycling) or such is stored in the non-volatile memory. Then, the guarantee information of the replacement member is read from the non-volatile memory when it is determined whether the process cartridge is to be recycled. Then, the part having reached the service lifetime is replaced.
According to Patent Document 2, non-volatile storing means is provided to a frame in which replaceable parts and/or devices are held, and service lifetime information of the individual ones of the replaceable parts and/or devices is stored in the non-volatile storing means. Thereby, it is possible to determine whether there are parts/devices, service lifetimes of which have been expired, from the service lifetime information of the individual ones of the replaceable parts and/or devices in the frame. Thus it is possible to easily carry out the replacement work.
Further, according to Patent Document 2, the replaceable parts and/or devices in an image forming unit are configured to be individually removable from the frame. Therefore, it is possible to remove from the frame and replace only parts/devices for which service lifetimes have been expired.
It is noted that a degree of degradation of a member that is degraded due to aging is different depending on an operating environment of the member, and there are many members for which degrees of degradation are different depending on operating temperatures. Therefore, the degree of degradation used for determining the service lifetime from operating information is to be one assuming that the operating environment is the upper limit (i.e., the worst end) of the operating guarantee range. Therefore, there may be a case where even when a service life actually remains for being able to be further used, the member is replaced when it is determined whether it is to be reused.
Generally speaking, a service lifetime of a member is doubled when an ambient temperature is reduced by 10° C. (according to the Arrhenius theorem). For example, assuming that the upper limit of the operating guarantee range is 35° C., in a case where a member having “limit of usable period of time=5 years in 35° C. environment (the upper limit of the operating guarantee range)” has been used as “actual condition=5 years in 25° C. environment”, the member can be used for a further 5 years in 25° C. environment. Notwithstanding, it would normally be determined that the member's usable period of time has expired since the determination would be made assuming the upper limit of the operating guarantee range of 35° C. On the contrary, in a case where the member having “limit of usable period of time=operating for 5 years in 35° C. environment (the upper limit of the operating guarantee range)” has been used under “actual condition=operating for 5 years in 45° C. environment”, the member will be continuously used notwithstanding the limit of usable period of time actually having already expired after the elapse of 2.5 years. As a result of the member being thus continuously used for which the limit of usable period of time has been already expired as mentioned above, an image being formed in the image forming apparatus may be degraded, or another member or a device may be degraded.
According to Japanese Laid-Open Patent Application No. 2004-45640 (Patent Document 3), the temperature of a printed circuit board on which electric components are mounted is measured, a degree of degradation is obtained from the measured operating temperature, and by using the degree of degradation, the remaining service lifetimes of the electric components are predicted. Therefore, it is possible to precisely know the remaining service lifetimes of the electric components mounted on the printed circuit board, and it is possible to avoid unnecessary replacement otherwise occurring when it is determined whether the components are to be further used.
Further, according to Patent Document 3, the ambient temperature of a target component is predicted from a temperature measurement result of another component, and thus, it is possible to reduce the number of temperature detecting devices.
However, according to Patent Document 3, the temperature detecting devices may be provided only for the purpose of determining the remaining service lifetimes. Thereby, a cost increase may occur.
Further, according to Patent Document 3, a member other than those mounted on the printed circuit board, for example, a photosensitive member, is not considered. Therefore, in a case where the image forming apparatus is, for example, a reuse apparatus (i.e., an apparatus having been collected from the market then being reused after maintenance) or the image forming apparatus includes a reuse cartridge, the past operating environment of the photosensitive member or such of the reuse apparatus or the reuse cartridge is unknown. Therefore, any member which is degraded due to aging should be replaced when it is determined whether the member is to be reused. Therefore, notwithstanding it being not necessary to replace a member (because the member still has a sufficient service lifetime) according to the actual operating environment, the member will be replaced because the actual operating environment thereof is unknown.
Further, Patent Document 3 may not contribute to “Reduction” of preventing a member having been collected from the market and still having a service lifetime from being replaced or dumped as waste.